Method to Improve Halogenation Reactions

ABSTRACT

In the halogenation reaction of organic olefin compounds, an excess amount of halogen gas (fluorine, chlorine, vaporized bromine and iodine, or their combination) is normally used in order to achieve as complete as possible conversion of the organic starting material. In a conventional process, the excess halogen gas in the off-gas stream is scrubbed by caustic solution which increases the consumption of halogen and generates waste for disposal. The present invention provides a novel process to recover and reuse the excess halogen gas and thus reduce the operating cost of the process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of commonly owned, copending U.S.patent application Ser. No. 14/873,346, filed Oct. 2, 2015, now U.S.Pat. No. 9,______. The '346 Application claims domestic priority fromcommonly owned, copending, U.S. Provisional Patent Application Ser. No.62/060,272, filed 6 Oct. 2014. The disclosures of these applications arehereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

In typical halogenation reactions of olefin or halo-olefin compounds(i.e., organic), an excess amount of halogen gas (fluorine, chlorine,bromine, iodine, or their combinations) is normally used in order toachieve maximum halogenation of the organic. In a conventionalhalogenation process, one reactor is used and the excess halogen gas inthe off-gas stream is scrubbed by a caustic solution. This increases theconsumption of halogen and generates waste for later disposal. Thepresent invention is directed to a novel process which permits recoveryof the excess halogen gas, which thereby reduces the operating cost ofthe reaction.

SUMMARY OF THE INVENTION

The present invention is a novel process which permits recovery of theexcess halogen gas, which thereby reduces the operating cost of thereaction. The process described herein makes use of two reactors insteadof one, a main reactor and a “clean-up” reactor. The main reactor isused to conduct the halogenation reaction in a conventional manner. Theclean-up reactor is charged with the same organic starting material asused in the main reactor.

During the operation of the main reactor an excess amount of halogen gasis fed into the main reactor and this reacts with the organic. Unreactedexcess halogen gas in the off-gas stream is directed into the clean-upreactor and there the halogen gas is captured by the organic startingmaterial held in the clean-up reactor. In order to fully remove thehalogen gas, the amount of the organic in the clean-up reactor is instoichiometric excess compared to the amount of halogen gas in theoff-gas stream from the main reactor. The process can be operated ineither batch or continuous mode.

In a batch operation, a fixed amount of organic is charged into both themain reactor and the clean-up reactor. Then, halogen gas is introducedinto the main reactor until the designated amount of halogen gas is fedinto the main reactor (normally, 1.1 to 1.5 times of halogen gas toorganic molar ratio by stoichiometric). The excess amount of halogen gasin the off-gas stream reacts with the organic in the clean-up reactor.The partially reacted organic in the clean-up reactor can be temporallystored and charged into the main reactor soon after as the startingmaterial for next batch of operation.

In a continuous operation, the organic is charged into both the mainreactor and the clean-up reactor. The main reactor runs in batch mode toprepare for the continuous operation. After the main reactor is wellbatched, halogen gas and the organic are continuous fed into the mainreactor with halogen gas in excess (normally, 1.1 to 1.5 times ofhalogen gas to organic molar ratio by stoichiometric). At the same time,fresh organic is also fed into the clean-up reactor continuously orperiodically. The excess amount of halogen gas in the off-gas streamreacts with the organic in the clean-up reactor. The partially reactedorganic from the clean-up reactor is continuously or periodicallydischarged from the clean-up reactor and fed into the main reactor tofurther react with the halogen gas.

Both main reactor and clean-up reactor can be continuous stirred tankreactors (CSTR) and/or plug flow reactors, or any other suitable type ofreactor for halogenation reactions. Both of the reactors can be eitherempty or packed with any halogen-resistant material to assist with thereaction. In some embodiments, the packing material comprises StainlessSteel, Inconel, Monel, other metal alloys, and the like. In someembodiments, the packing material comprises fluorocarbon plastics, suchas PFA, PTFE, and the like.

As an example, this process can be used in the chlorination of1,1,3-trichloropropene (HCC-1240za) to make 1,1,1,2,3-pentachloropropane(HCC-240db).

It should be appreciated by those persons having ordinary skill in theart(s) to which the present invention relates that any of the featuresdescribed herein in respect of any particular aspect and/or embodimentof the present invention can be combined with one or more of any of theother features of any other aspects and/or embodiments of the presentinvention described herein, with modifications as appropriate to ensurecompatibility of the combinations. Such combinations are considered tobe part of the present invention contemplated by this disclosure.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed. Other embodimentswill be apparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a convention halogenation reactor system, employing onereactor and a scrubber to handle excess halogen.

FIG. 2 shows an embodiment of the halogenation reactor system of thepresent invention, employing one main reactor and a second clean-upreactor.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 2, the present invention introduces a second reactor (aclean-up reactor) into the process of halogenation reaction ofolefin/halo-olefin, which can recover the excess halogen gas and reducethe operating cost. Both main reactor and clean-up reactor can be CSTRand/or plug flow reactors, or any other type of halogenation reactors.As an example, this process can be used in the chlorination ofHCC-1240za to make HCC-240db.

The process can be operated in either batch or continuous mode. In abatch operation, a fixed amount of organic is charged into both the mainreactor and the clean-up reactor. Then, halogen gas is introduced intothe main reactor until the designated amount of halogen gas is fed intothe main reactor (normally, from 1.1 to 1.5 times of halogen gas toorganic molar ratio by stoichiometry). The excess amount of halogen gasin the off-gas stream reacts with the organic in the clean-up reactor.The partially reacted organic in the clean-up reactor can be temporallystored and charged into the main reactor as the starting material fornext batch operation.

In a continuous operation, the organic is charged into both the mainreactor and the clean-up reactor. The main reactor runs in batch mode toprepare for the continuous operation. After the main reactor is wellbatched, halogen gas and the organic are continuous fed into the mainreactor with halogen gas in excess (normally, 1.1 to 1.5 times ofhalogen gas to organic molar ratio by stoichiometry). At the same time,fresh organic is also fed into the clean-up reactor continuously orperiodically. The excess amount of halogen gas in the off-gas streamreacts with the organic in the clean-up reactor. The partially reactedorganic from the clean-up reactor is continuously or periodicallydischarged from the clean-up reactor and fed into the main reactor tofurther react with the halogen gas.

Example 1 HCC-240db Synthesis—Batch Operation

A 500 ml main reactor equipped with a Cl₂ gas sparger and a totalcondenser is charged with 250 g of 1,1,3-trichloropropene (99.5 wt %pure). The reactor is stirred and heated using an oil bath which hasbeen preheated to 80° C. After the reactor temperature reaches 80° C.,Cl₂ gas is fed into the reactor via the gas sparger. The reactortemperature is controlled at 80° C.±5° C. by controlling the feed rateof Cl₂ gas and adjusting the oil bath temperature setting. During theoperation, the total Cl₂ feed is maintained at 110-120 mol % of1,1,3-trichloropropene charged into the reactor, and HCC-240db isremoved as crude product for further purification.

Excess Cl₂ gas from the main reactor is fed to a clean-up reactorcontaining 250 g of 1,1,3-trichloropropene (99.5 wt % pure) therebyforming additional crude HCC-240db, which is recycled to the mainreactor.

Example 2 HCC-240db Synthesis—Continuous Operation

A 500 ml main reactor and a 500 ml clean-up reactor both equipped with aCl₂ gas sparger and a total condenser are charged with 250 g of1,1,3-trichloropropene (99.5 wt % pure), respectively. Both reactors arestirred and heated using oil baths which have been preheated to 80° C.

After both reactor temperatures reach 80° C., Cl₂ gas is fed into themain reactor via the gas sparger. The reactor temperature is controlledat 80° C.±5° C. by controlling the feed rate of Cl₂ gas and adjustingthe oil bath temperature setting. The off-gas from the main reactor isfed into the clean-up reactor via the sparger. After about 140 g of Cl₂is fed into the main reactor, the continuous operation is started byfeeding fresh 1,1,3-trichloropropene into the clean-up reactor at about125 g/h, Cl₂ into the main reactor at about 135 g/h, and drawing offHCC-240db from the main reactor at about 186 g/h. The organic in theclean-up reactor is continuously transferred to the main reactor at anappropriate rate which maintains stable level in both reactors.

Example 3 HCC-240db Synthesis—Continuous Operation

A 500 ml main reactor and a 500 ml clean-up reactor both equipped with aCl₂ gas sparger and a total condenser are charged with 372 g ofHCC-240db (99.5 wt % pure) for the main reactor and 250 g of1,1,3-trichloropropene (99.5 wt % pure) for the clean-up reactor,respectively. Both reactors are stirred and heated using oil baths whichhave been preheated to 80° C.

After both reactor temperatures reach 80° C., Cl₂ gas is continuouslyfed into the main reactor via the gas sparger at about 135 g/h, fresh1,1,3-trichloropropene is continuously fed into the clean-up reactor atabout 125 g/h, and HCC-240db is continuously drawn-off from the mainreactor at about 186 g/h. At the same time, the organic in the clean-upreactor is continuously transferred to the main reactor at anappropriate rate which maintains stable level in both reactors. Bothreactor temperatures are controlled at 80° C.±5° C. by adjusting the oilbath temperature setting.

As used herein, the singular forms “a”, “an” and “the” include pluralunless the context clearly dictates otherwise. Moreover, when an amount,concentration, or other value or parameter is given as either a range,preferred range, or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

It should be understood that the foregoing description is onlyillustrative of the present invention. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the invention. Accordingly, the present invention isintended to embrace all such alternatives, modifications and variancesthat fall within the scope of the appended claims.

What is claimed is:
 1. A process for the halogenation reaction of anorganic starting material comprising olefin compounds comprising thesteps of: (a) conducting the halogenation reaction of the organicstarting material in a first reactor using excess halogen, and (b)conducting the halogenation reaction of the organic starting material ina second reactor using the excess halogen from step (a) to halogenate anexcess amount of the organic starting material contained in the secondreactor.
 2. The process of claim 1, wherein the reactors used in theprocess are halogenation reactors selected from the group consisting ofCSTR, plug flow reactor, and combinations thereof.
 3. The process ofclaim 1, which is conducted in a batch mode.
 4. The process of claim 1,which is conducted in a continuous mode.
 5. The process of claim 1,wherein the halogen gas used in the process is selected from the groupconsisting of fluorine, chlorine, bromine, iodine, and combinationsthereof.
 6. The process of claim 1, wherein the reactors can be eitherempty or packed with a halogen-resistant material to assist with thereaction.
 7. The process of claim 6, wherein at least one reactorincludes a packing material.
 8. The process of claim 7, wherein thepacking material is selected from the group consisting of StainlessSteel, Inconel, Monel, and metal alloys.
 9. The process of claim 7,wherein the packing material comprises fluorocarbon plastics.
 10. Theprocess of claim 9, wherein the packing material comprises PFA.
 11. Theprocess of claim 9, wherein the packing material comprises PTFE.